MANET (Mobile Ad-Hoc Networking) and DTN (Delay Tolerant Networking)

For nodes to form networks without any infrastructure requires that some mechanism exist for discovery of the nodes in the network, and for routes to be found and maintained as nodes move about. Connectivity could change and might also be episodic, so nodes will need to deal with additional delay in some cases, beyond what might normally be expected on an infrastructure based network.

This work has examined the enabling and performance of MANET, DTN, and multihop communication directly between end-nodes that form the network itself, as well as acting as the nodes that send and receive data for end-users.

S. N. Bhatti, R. Atkinson, J. Klemets. Integrating Challenged Networks. MILCOM 2011 - 30th IEEE Military Communications Conf.. Baltimore, MD, USA. Nov 2011.
| PDF | .bib | 10.1109/MILCOM.2011.6127596 | abstract For a comprehensive information coverage across theatre, it is necessary to integrate many different sources of data which are likely to use protocols specific to a specialised purpose. For example, resource-constrained or challenged networks such as sensor systems and MANET systems, using their own protocols, may be used in conjunction with other Internet Protocol (IP) based communication and need to be integrated into the GIG. While such integration may be possible today, the engineering is complex and the resultant system may be difficult to configure and maintain, as well as being brittle when systems changes or reconfiguration is required. Furthermore, when security and identity issues are considered, the additional overhead for enabling integration within the context of sensor systems and MANETs raises challenging technology issues. Based on our ongoing work, we present a potential solution which organises such systems based on identity and location, but allows integration with Internet- wide communication. G. Bigwood, T. Henderson, S. Bhatti. Social Delay-Tolerant Network Routing. WWCSS 2009 - 2nd Winter Workshop on Complexity in Social Systems. Institute for Complexity Sciences, Lisbon, Portugal. Jan 2009.
| PDF | .bib | abstract Routing in mobile delay-tolerant networks faces new challenges such as mobility and the dynamic nature of the network. Social network information may be useful for routing since mobile nodes in the same social network may be encountered more often and thus be more successful at message-passing. Collecting this social network information, however, can be challenging. We compare a social network traced from user encounters with a user-declared social network, and show some of the differences between these two networks. Y. Huang, S. Handurukande, S. N. Bhatti. Autonomic MANET Routing Protocols. JNW - Journal of Networks, vol. 4, no. 8, pages 743-753. Oct 2009.
| PDF | .bib | 10.4304/jnw.4.8.743-753 | abstract In Mobile Ad hoc Networks (MANETs), timers have been used widely to maintain routing (state) information. The use of fixed- interval timers is simple to implement but, in practise, may be difficult to configure in dynamic operational environments, and so may give reduced performance in the presence of frequent topology changes. This paper proposes a self-tuning timer approach within a simple control system for MANET routing protocols with the aim of allowing dynamic, autonomic, re-calibration of routing update frequencies. A novel dynamic timer algorithm is presented to automatically tune routing performance by adapting timer intervals to network conditions. Our simulation results have shown that, compared to the default fixed timer approach, the proposed algorithm could effectively improve routing throughput without manual configuration. G. Kannan, Y. Huang, S. N. Bhatti, S. Merchant, U. Desai. A Cross Layer Routing Protocol for Multihop Cellular Networks. WPC - Wireless Personal Communications, vol. 51, no. 3, pages 427-447. Nov 2009.
| PDF | .bib | 10.1007/s11277-009-9751-y | abstract We propose a cross-layer routing protocol for a Code Division Multiple Access (CDMA) Multihop Cellular Network (MCN). In designing the routing protocol for MCN, multiple constraints are imposed on intermediate relay node selection and end-to-end path selection. The constraints on relay nodes include willingness for cooperation, sufficient neighbourhood connectivity and the level of interference offered on the path. Path constraints include end-to- end throughput and end-to-end delay. A facile incentive mechanism is presented to motivate the cooperation between nodes in call forwarding. In addition, we present a route resilience scheme in the event of dynamic call dropping. In particular, a fast neighbour detection scheme for route resilience is proposed. Instead of using periodic HELLO messages as in traditional ad-hoc routing, the proposed neighbour detection scheme adopts an explicit handshake mechanism to reduce neighbour detection latency. We conclude the paper by demonstrating the superior performance of the proposed routing protocol compared with the other well known routing algorithms. Y. Huang, S. N. Bhatti, S.-A. Sorensen. The impact of topology update strategies on the performance of a proactive MANET routing protocol. IJPED - Intl. Journal of Parallel, Emergent and Distributed Systems, vol. 23, no. 6, pages 447-460. Oct 2008.
| PDF | .bib | 10.1080/17445760801945524 | abstract Although there have been a number of performance studies of proactive mobile ad hoc network (MANET) routing protocols, little attention has been paid to the impacts of topology update strategies on routing performance. This paper presents an analysis of several topology update strategies for a proactive MANET routing protocol. The goal of this paper is to better understand how topology update strategies can contribute to topology maintenance in proactive MANETs and thus impact the overall performance, based on simulations involving optimised link state routing (OLSR), a popular MANET protocol. Our contribution includes (1) a quantitative analysis of the impacts of proactive update intervals on the routing performance of OLSR; (2) evaluating the performance of reactive topology updates and proactive updates for OLSR. G. Bigwood, D. Rehunathan, M. Bateman, T. Henderson, S. N. Bhatti. Exploiting self-reported social networks for routing in ubiquitous computing environments. SAUCE 2008 - 1st Intl. Workshop on Social Aspects of Ubiquitous Computing Environments. Avignon, France. Oct 2008.
| PDF | .bib | 10.1109/WiMob.2008.86 | abstract Mobile, delay-tolerant, ad hoc and pocket-switched networks may form an important part of future ubiquitous computing environments. Understanding how to efficiently and effectively route information through such networks is an important research challenge, and much recent work has looked at detecting communities and cliques to determine forwarding paths. Such detected communities, however, may miss important aspects. For instance, a user may have strong social ties to another user that they seldom encounter; a detected social network may omit this tie and so produce sub-optimal forwarding paths. Moreover, the delay in detecting communities may slow the bootstrapping of a new delay-tolerant network. This paper explores the use of self-reported social networks for routing in mobile networks in comparison with detected social networks discovered through encounters. Using encounter records from a group of participants carrying sensor motes, we generate detected social networks from these records. We use these networks for routing, and compare these to the social networks which the users have self-reported on a popular social networking website. Using techniques from social network analysis, we find that the two social networks are different. These differences, however, do not lead to a significant impact on delivery ratio, while the self-reported social network leads to a significantly lower cost. Y. Huang, S. N. Bhatti. Fast-Converging Distance Vector Routing for Wireless Mesh Networks. WWASN 2008 - 5th Workshop on Wireless Ad hoc and Sensor Networks. Beijing, China. Jun 2008.
| PDF | .bib | 10.1109/ICDCS.Workshops.2008.83 | abstract A major concern about distance-vector routing protocols for wireless mesh networks is its slow convergence in the presence of link changes, which can potentially degrade network stability. This paper studies the impact of update intervals on network convergence and proposes a fast-converging distance-vector routing algorithm. Our simulation results have shown that the proposed algorithm could effectively reduce convergence latency and improve throughput without leading to a significant increase in control overhead. Y. Huang, G. Kannan, S. N. Bhatti, S. N. Merchant U. B. Desai. Route Dynamics for Shortest Path First Routing in Mobile Ad Hoc Networks. WTS 2008 - 7th IEEE Wireless Telecommunications Symp.. Pomona CA, USA. Apr 2008.
| PDF | .bib | 10.1109/WTS.2008.4547570 | abstract This paper investigates the route dynamics of shortest-path first (SPF) routing in mobile ad hoc networks (MANETs). In particular, we find, from a statistical analysis of route duration and route change interval, that route dynamics may require complex modelling. Our analysis considers various mobility models, node velocities and node densities of the MANET network. Our findings show that, in a MANET with moderate or high rate of mobility, the route duration could be approximated by an exponential distribution with approximate parameters, while the route duration of specific lengths could not. Our findings suggest that minimum hop-count routing in MANETs may be inappropriate and that further investigation is required in order to develop models that let us understand MANET route dynamics. Y. Huang, S. N. Bhatti, S. Handurukande. Autonomic Tuning of Routing for MANETs. ACNM 2008 - 2nd Workshop on Autonomic Communications and Network Management. Salvador da Bahia, Brazil. Apr 2008.
| PDF | .bib | 10.1109/NOMSW.2007.49 | abstract In mobile ad hoc networks (MANETs), timers have been widely used to maintain routing (state) information. The use of fixed- interval timers is simple to implement but, in practise, may be difficult to configure in dynamic operational environments, and so may give reduced performance in the presence of frequent topology changes. This paper proposes a self-tuning timer approach within a simple control system for MANET routing protocols with the aim of allowing dynamic, autonomic, re-calibration of routing update frequencies. A novel dynamic timer algorithm is presented to automatically tune routing performance by adapting timer intervals to network conditions. Our simulation results have shown that, compared to the default fixed timer approach, the proposed algorithm could effectively improve routing throughput without manual configuration. Y. Huang, S. N. Bhatti, S.-A. Sorensen. Self-Tuning Network Support for MANETs. NOMS 2008 - IEEE Network Operations and Management Symposium. Salvador da Bahia, Brazil. Apr 2008.
| PDF | .bib | 10.1109/NOMS.2008.4575275 | abstract Rapid and unpredictable topology changes and resource constraints make delivering packets in a MANET (mobile ad hoc network) a challenging task. Routing information has to be updated to reflect the topology changes and maintain the correctness of route selection. On the other hand, the dissemination of control messages has to be optimised for efficient resource usage and to alleviate channel contention problems. To solve this problem, this dissertation focuses on how to automatically tune routing performance for MANETs in terms of packet delivery ratio and control overhead. The impacts of soft state signalling, especially the refresh intervals, are studied under various scenarios. A variety of topology advertisement strategies are presented. Two self-tuning neighbour detection schemes are proposed, the dynamic timer algorithm and the fast neighbour handshake algorithm, in order to enhance routing performance. Y. Huang, S. N. Bhatti, S.-A. Sorensen. Reducing Neighbour Detection Latency in OLSR. PIMRC 2007 - 18th IEEE Intl. Symp. Personal, Indoor and Mobile Radio Communications. Athens, Greece. Sep 2007.
| PDF | .bib | 10.1109/PIMRC.2007.4394779 | abstract This paper presents a fast neighbour detection scheme for a proactive MANET routing protocol. Instead of using periodic HELLO messages, the proposed scheme adopts explicit handshake mechanism to reduce the latency in neighbour detection. In particular, two route handshake options are presented, namely the Broadcast based handshake (BHS) algorithm and Unicast based handshake (UHS) algorithm. Our simulation results show that the proposed scheme improves routing performance, especially in networks with moderate or high mobility. In low-density networks, the unicast option improves the routing throughput significantly without introducing extra control overhead. Y. Huang, S. N. Bhatti, S.-A. Sorensen. Analysing the Impact of Topology Update Strategies on the Performance of a Proactive MANET Routing Protocol. WWASN 2007 - 4th Workshop on Wireless Ad hoc and Sensor Networks, Toronto. Ontario, Canada. Jun 2007.
| PDF | .bib | 10.1109/ICDCSW.2007.22 | abstract This paper presents an analysis of several topology update strategies for proactive MANET routing protocols. Although there have been a number of performance studies of proactive MANET routing protocols, little attention has been paid to the impacts of topology update strategies on routing performance. The goal of this paper is to better understand how topology update strategies can contribute to topology maintenance in proactive mobile ad hoc networks and thus impact the overall performance. Our contribution includes (1) a quantitative analysis on the impacts of proactive update intervals on the routing performance; (2) evaluating the performance of reactive topology updates and proactive updates for proactive routing protocols. Y. Huang, S. N. Bhatti, S.-A. Sorensen. Adaptive MANET Routing for Low Overhead. ADAMUS 2007 - 1st IEEE WoWMoM Workshop on Adaptive and DependAble Mission- and bUsiness-critical mobile Systems. Helsinki, Finland. Jun 2007.
| PDF | .bib | 10.1109/WOWMOM.2007.4351682 | abstract In wireless mission-critical systems, systems may be resource-constrained including limited bandwidth, so minimising protocol overhead, whilst maintaining performance, is important. Proactive MANET routing protocols tend to provide smaller route discovery latency than on-demand protocols because they maintain route information to all the nodes in the network at all time. However, such protocols may impose excessive soft-state routing control overhead which is generated by disseminating periodic update messages. In order to mitigate the side effects of the soft-state control over-heads, we propose two adaptive proactive routing algorithms, namely DT_MIAD and DT_ODPU. By tuning the value of refresh intervals dynamically and automatically, refresh updates are triggered based on traffic conditions and node mobility. We show through simulations that the proposed adaptive routing algorithms can outperform a traditional proactive routing protocol (OLSR). R. Atkinson, M. Lad, S. N. Bhatti, S. Hailes. A Proposal for Coalition Networking in Dynamic Operational Environments. MILCOM 2006 - 25th IEEE Military Communications Conf.. Washington DC, USA. Oct 2006.
| PDF | .bib | 10.1109/MILCOM.2006.302077 | abstract At present, military communications within battlefields are very restricted, both by policy and due to technology limitations. In Southwest Asia today, there are needlessly long and complex communications paths, often involving multiple relays and use of constrained-bandwidth MILSATCOM back-haul outside the theatre, when nearby forces could communicate directly via existing interoperable radios. This is a current problem for NATO and Coalition forces. The current Internet protocol suite lacks core support for mobility, scalable support for multi-homed nodes, and does not provide the capabilities needed for optimal communications in forward operating areas. We propose a coalition-based, multi-homed approach leveraging both local-area and wide-area connectivity, improving both the flexibility and robustness of communication, without conflicting with the security policy of sensitive communication. The Coalition Peering Domain (CPD) is a distributed, self-configuring architecture that supports the secure, collaborative networking relationships needed to provide this flexibility and robustness. The CPD facilitates the inter-connection of cooperating, but administratively separate, network segments. The CPD exploits multi-homed and multi-path communication to better-utilise all available connectivity. The identifier-locator network protocol (ILNP) provides native support for improved scalability in multi-homing and mobility, while easing use of network layer security and allowing inter-operation across different administrative domains. Our approach is compatible with current work in mobile ad-hoc networking (MANET). ILNP has excellent compatibility with IPv6: existing IPv6 backbone networks do not require any modification to carry ILNP traffic natively. There are practical, realistic and deployable engineering solutions to realise the CPD and ILNP within the framework of IPv6. Y. Huang, S. N. Bhatti, S.-A. Sorenson. A Comparison of Temporal and Topological Soft State Updates for a Proactive MANET Routing Protocol. LCS 2006 - London Communications Symp.. London, UK. Sep 2006.
| PDF | .bib | abstract In an mobile ad hoc networks (MANET), each node maintains routing information about other nodes in the network at all times. The nodes propagate state refresh messages to maintain correct routing information. In this paper we present a quantitative analysis on the impact of temporal updates and topological updates for a proactive MANET routing protocol and assess its impact on performance. Simulation results show that the temporal state updates have a significant impact on the throughput, while the topological state updates do not. Furthermore, frequent topological state updates in relatively high-density networks lead to performance degradation because of the large overhead introduced. Y. Huang, S. N. Bhatti, D. Parker. Tuning OLSR. PIMRC 2006 - 17th IEEE Intl. Symp. Personal, Indoor and Mobile Radio Communications. Helsinki, Finland. Sep 2006.
| PDF | .bib | 10.1109/PIMRC.2006.254160 | abstract Optimised link state routing (OLSR) is a popular protocol for use in MANET networks. In this paper, we investigate the different impacts of tuning refresh interval timers on OLSR performance under various scenarios (varying node density and node speed). Based on the simulation results with NS2, we find that although reducing refresh intervals could improve OLSR's performance, the intervals for some message types (HELLO messages) have a bigger impact on OLSR performance than for other message types. We find that the impact of the interval timer grows with increased network mobility and node density. S. G. Methley, M. Crisp, J. Newman, M. Rio, S. Bhatti P. A. Ramsdale, A. Atefi. Efficient mobile mesh networking: attractions, myths and techno-economic roadmap to successful commercial innovation. DySpan 2005 - 1st IEEE Intl. Symp. New Frontiers in Dynamic Spectrum Access Networks. Baltimore, MD, USA. Nov 2005.
| PDF | .bib | 10.1109/DYSPAN.2005.1542653 | abstract This paper examines four scalability hypotheses of interest for mobile meshes via the following questions: 'Do meshes self- generate capacity as new nodes join?' 'Are meshes more spectrally efficient?' 'Do directional antennas confer significant benefits for hand-held below 3.5 GHz?' 'No' is the answer because these hypotheses, whilst having a theoretical basis, can be shown to rely on inappropriate real world assumptions. However the following hypothesis is found to be true: 'Meshes may improve spectrum utilization'. Importantly however, there remain properties of meshes which make them uniquely attractive, such as coverage extension. However this raises a further question over the ability of mobile mesh architecture to provide a guaranteed quality of service. Finally, the wider aspects of commercial innovation are considered S. G. Methley, M. Crisp, J. Newman, M. Rio, P. A. Ramsdale, S. Bhatti, A. Atefi. Efficient Mobile Mesh Networking:Testing Scalability Hypotheses. 6th IEE Intl. Conf. 3G and Beyond. London, UK. Nov 2005.
| PDF | .bib | abstract This paper examines four scalability hypotheses of interest for mobile meshes via the following questions: 'Do meshes self- generate capacity as new nodes join?' 'Are meshes more spectrally efficient?' 'Do directional antennas confer significant benefits for hand-helds below 3.5GHz?' 'No' is the answer because these hypotheses, whilst having a theoretical basis, can be shown to rely on inappropriate real world assumptions. However the following hypothesis is found to be true: 'May meshes improve spectrum utilisation?'